Method for manufacturing a pressure vessel liner

Abstract

This invention provides a technology for continuously forming liners for pressure vessels that are easy to bend. [Solution] The liner of a pressure vessel comprises a main body having a central portion and a tapered portion, and a plurality of connecting portions that connect two adjacent main body portions in series via the tapered portion, and which have a smaller diameter than the central portion and are bent to fold the main body portion. The liner is manufactured by extruding a cylindrical preform having a predetermined inner diameter, and placing a cylindrical molding auxiliary member having an outer diameter corresponding to the inner diameter of the connecting portion inside the portion of the preform corresponding to the connecting portion, and hollow molding the liner while the auxiliary member is in contact with the inside of the connecting portion.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a method for manufacturing a liner of a pressure vessel and the like.

Background Art

[0002] Conventionally, a pressure vessel for storing a fluid is known to have a structure that alternately includes a main body portion having a cylindrical shape and a connection portion having a cylindrical shape but a smaller diameter than the main body portion as a liner (Patent Document 1, FIG. 5c, etc.). For this type of liner, for example, when manufacturing a liner before bending by continuously hollow-molding a cylindrical body extruded by a pair of rotary die sets into a main body portion and a connection portion with a small diameter. This method is advantageous in that the liner can be formed into the main body portion and the connection portion at once and continuously. Thereafter, by bending the connection portion of this liner by bending and folding the main body portion, a folded pressure vessel can be obtained.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in this liner, since a cylindrical body with a certain wall thickness is continuously formed into a large-diameter main body portion and a small-diameter connection portion, in the connection portion with a small diameter, the wall thickness tends to increase compared to the main body portion. Also, in the connection portion, unevenness in wall thickness may occur.

[0005] In such a case, when bending the liner, in the connection portion, due to the increase in wall thickness and unevenness in wall thickness, it is difficult to apply a uniform load, so bending may become difficult. For this reason, the production efficiency of bending may decrease, and it may also become difficult to make the shape of the connection portion uniform.

[0006] This specification provides a technique for continuously forming liners for pressure vessels that are easily bendable. [Means for solving the problem]

[0007] This specification is embodied in a method for manufacturing a liner for a pressure vessel. The liner comprises a main body having a central portion and a tapered portion, and a plurality of connecting portions that connect two adjacent main body portions in series via the tapered portion, and which have a smaller diameter than the central portion and are bent to fold the main body portion. The method for manufacturing the liner comprises a step of extruding a cylindrical preform having a predetermined inner diameter, and then hollow molding the preform by placing a cylindrical molding auxiliary member having an outer diameter corresponding to the inner diameter of the connecting portion inside the portion of the preform corresponding to the connecting portion, and bringing the auxiliary member into contact with the inside of the connecting portion.

[0008] According to this liner manufacturing method, by bringing the molding auxiliary member into contact with the inside of the portion corresponding to the connecting portion, the connecting portion can be formed to the desired and uniform thickness, thereby obtaining a connecting portion having the intended thickness, inner diameter, and shape. As a result, bending of the connecting portion of the liner can be easily performed.

[0009] Another embodiment of this manufacturing method may include using a die set comprising a plurality of pairs of dies arranged opposite each other on a predetermined track. This allows for the efficient production of the liner.

[0010] Another embodiment of this manufacturing method may include the step of forming the connection portion so as to provide a groove on the inner outer surface when bent. This makes it possible to manufacture a liner with a connection portion that is even easier to bend.

[0011] Another embodiment of this manufacturing method may further include a step of bending the connecting portion of the liner to fold the main body portion.

[0012] This specification also embodies a liner for a pressure vessel. The liner comprises a main body having a central portion and a tapered portion, and a plurality of connecting portions that connect two adjacent main bodies in series via the tapered portion, and which are smaller in diameter than the central portion and bent to fold the main body, The connecting portion has a thickened portion between it and at least one of the adjacent tapered portions.

[0013] According to this liner, by providing a thicker section at the tapered end of the connection, the increase in wall thickness at the connection is suppressed, and bending at the connection is made easier. [Brief explanation of the drawing]

[0014] [Figure 1] This diagram shows a schematic of the manufacturing process for pressure vessel liners. [Figure 2] This figure shows an example of a molding apparatus. [Figure 3] This figure shows the state of the liner connection during molding. [Figure 4] This figure shows the state during molding when a groove shape is created at the connection point. [Modes for carrying out the invention]

[0015] The methods for manufacturing the liners of pressure vessels disclosed herein will be described below with reference to the drawings as appropriate. In this specification, the fluids stored in the pressure vessels are not particularly limited, but examples include hydrogen, natural gas, helium, dimethyl ether, liquefied petroleum gas, xenon, etc.

[0016] Pressure vessels are typically formed by folding a braided structure of fiber-reinforced plastic material, such as CFRP, into a predetermined shape on the surface of the liner 100. The braided structure is integrated with the surface of the liner 100 or the liner 110 after bending, for example, before or simultaneously with bending the liner 100. For the sake of explanation, the braided structure will be omitted in the following description.

[0017] FIG. 1 shows a part of the liner 100 of the pressure vessel before bending in the upper part and the liner 110 after bending in the lower part. FIG. 2 shows an example of the molding device 200, FIG. 3 shows a cross-section during the molding of the connecting part 20, and FIG. 4 shows a cross-section when a groove shape is imparted to the surface of the connecting part 20 for molding. In FIGS. 2 to 4, the preform 30 moves from the left side to the right side in the figure. First, the outline of the liner 100 will be described, and then the manufacturing method of the liner 100 will be explained.

[0018] As shown in the upper part of FIG. 1, the liner 100 has a form in which a plurality of main body parts 10 and a plurality of connecting parts 20 are alternately arranged in series. The main body part 10 includes a central part 12 and a tapered part 14. The central part 12 has a cylindrical form extending with a predetermined diameter. The tapered part 14 gradually becomes smaller in diameter from the central part 12 and has a tapered shape that matches the diameter of the connecting part 20.

[0019] The connecting part 20 has a cylindrical form with a smaller diameter than the central part 12. The connecting part 20 connects adjacent main body parts 10 via the tapered part 14. The connecting part 20 is configured to be bent so that the main body part 10 can be folded. By adopting a form in which a plurality of main body parts 10 and a plurality of connecting parts 20 are alternately connected in series, the folded liner 110 shown in the lower part of FIG. 1 can be obtained.

[0020] The liner 100 is formed by blow molding (hollow molding) using a cylindrical preform (parison) obtained by extruding a resin material of a predetermined composition with a mold having a molding surface corresponding to the main body part 10 and the connecting part 20. Since the liner 100 is intended to be folded, it is formed as a long body. For this reason, it is preferable to be continuously integrally formed by continuous blow molding.

[0021] Among them, as shown in FIG. 2, it is preferable to perform blow molding with a molding apparatus 200 provided with a mold set 40 on a predetermined orbit Z. According to the molding apparatus 200, in cooperation with the extrusion of the preform 30, the mold set 40 is moved, and a plurality of main body portions 10 and a plurality of connecting portions 20 can be continuously formed alternately from the preform 30. The mold set 40 is composed of a pair of molds 42, 44, 46 arranged to face the extruded preform 30. The mold set 40 is configured to be able to form a unit structure including at least one main body portion 10 and at least one connecting portion 20. The molding apparatus 200 also includes an extrusion molding apparatus (not shown) that extrudes the preform 30 and extrudes it into the mold set 40.

[0022] Further, in this molding apparatus 200, a molding auxiliary member 50 is arranged along the extrusion direction of the preform 30 inside the preform 30 from the vicinity of the extrusion port of the preform 30. The molding auxiliary member 50 has a length substantially equivalent to the range where the molds 42, 44, 46 of the mold set 40 are arranged. The molding auxiliary member 50 is, for example, a metal pipe.

[0023] As shown in FIG. 3, the molding auxiliary member 50 has a plurality of vent holes 52, and by blowing pressurized gas into the inside of the preform 30 through the hollow portion of the molding auxiliary member 50, the pressurized gas can be uniformly supplied into the preform 30.

[0024] The outer diameter of the molding auxiliary member 50 is set so as to impart the intended wall thickness to the connecting portion 20 by the molding surfaces of the molds 42, 44, 46 constituting the mold set 40 and the outer surface of the molding auxiliary member 50.

[0025] The outer shape of the molding auxiliary member 50 is not particularly limited. For example, it is not particularly limited to a circular shape, an elliptical shape, a square shape, etc. The shape of the connecting portion 20 is defined by the outer shape of the molding auxiliary member 50.

[0026] To mold the liner 100, a pre-molded body 30 is first formed by melting and extruding a resin material of a predetermined composition. The resin material of the liner 100 is not particularly limited, but examples include one or more resin materials selected from polyamide (PA), ethylene vinyl alcohol (EVOH), high-density polyethylene (HDPE), ethylene vinyl acetate (EVA), and linear low-density polyethylene (LLDPE). The liner 100 may have a one-layer or multilayer structure of two or more layers using these resin materials. Furthermore, considering bending, it may also contain an elastomer material such as rubber.

[0027] As shown in Figure 3, the continuously extruded pre-molded body 30 enters the track Z on which the mold set 40 is positioned opposite each other, and is gradually closed by the mold 42, etc. Simultaneously with the closing of the mold, pressurized gas is blown into the interior of the pre-molded body 30 via the molding auxiliary member 50.

[0028] Because the molding auxiliary member 50 is positioned inside the pre-molded body 30, at the molding portion of the connection portion 20 of the pre-molded body 30, the molding auxiliary member 50 is in contact with the molding surface of the connection portion 20 in the mold set 40 when the mold is closed, and the connection portion 20 is molded in a manner similar to press molding. As a result, the connection portion 20 can be molded to the intended thickness and shape. As the pre-molded body 30 moves along the extrusion direction, the molding portion of the connection portion 20 of the pre-molded body 30 is in contact with the molding auxiliary member 50 at least once and molded in a manner similar to press molding. The connection portion 20 is initially press-molded by the molding auxiliary member 50 and the molding portion of the connection portion 20 in the mold set 40, but then, as the pre-molded body 30 moves along the trajectory Z, the molding portion of the connection portion 20 moves away from the molding auxiliary member 50. While not in contact with the molding auxiliary member 50, the molding portion is molded by pressurized gas.

[0029] Furthermore, when the connecting portion 20 is formed by press molding between the molding auxiliary member 50 and the molding surface of the mold set 40, excess resin material may move to the tapered portion 14. As a result, a thickened portion 24 may be formed between the connecting portion 20 and an adjacent tapered portion 14. The thickened portion 24 is formed thickly over the entire inner circumference or a part thereof at the end of the connecting portion 20 closest to the tapered portion 14. The thickened portion 24 ensures the thickness and shape of the connecting portion 20 as intended by the molding auxiliary member 50. The thickened portion 24 may be formed, for example, between the connecting portion 20 and a tapered portion 14 located on the rear side in the extrusion direction. Alternatively, the thickened portion 24 may be formed between the connecting portion 20 and both of two adjacent tapered portions 14.

[0030] As shown in Figure 4, the molding surface of the mold set 40 for forming the connecting portion 20 can be provided with a convex molding portion 48 on its outer surface that corresponds to the inner side when the connecting portion 20 is bent, thereby providing a groove portion 22. This makes the bending process of the connecting portion 20 even easier.

[0031] Meanwhile, pressurized gas is supplied to the molding area of ​​the main body portion 10 of the pre-molded body 30 by the molding auxiliary member 50. As a result, the main body portion 10, defined by the molding surface of the mold set 40, is blow-molded.

[0032] Once the pre-molded body 30 is molded with the intended shape by the mold set 40, the mold set 40 is opened, and the liner 100, which alternately consists of the main body 10 and the connecting parts 20, is ejected onto the track Z.

[0033] The resulting liner 100 has the intended thickness at the connection portion 20, without any uneven thickness or thickness distribution. Furthermore, the connection portion 20 has the intended shape. As a result, when the liner 100 is bent in a subsequent process to obtain the liner 110, the bending process is easier, allowing the bending process to be carried out with excellent production efficiency and without shape defects.

[0034] In the above embodiments, the molding auxiliary member 50 extends along the length of the mold set 40, but it is not limited to this. The molding auxiliary member 50 may be provided in a range from near the extrusion opening of the pre-molded body 30 to a position where it reaches the molding area of ​​the first connection portion 20. In this case as well, since it is press-molded once by the molding auxiliary member 50, it becomes easier to set the wall thickness and shape as intended, and bending at the connection portion 20 can be facilitated.

[0035] Furthermore, in the above embodiments, the molding apparatus 200 performed blow molding using pressurized gas, but it can also be molded by vacuum forming. Also, in the above embodiments, a groove 22 was provided on the inner portion of the connecting portion 20 when bent, but it is not limited to this, and a curved or bent shape may also be provided on the outer portion of the connecting portion 20 when bent to facilitate bending. In this case, it is necessary to provide a predetermined shape to both the molding die set 40 and the molding auxiliary member 50.

[0036] Furthermore, although the above embodiments have described the liner 100 and the liner 110 after bending, this specification also provides a pressure vessel equipped with such liners 100 and 110, and a method for manufacturing a pressure vessel. The configuration and manufacturing method of a pressure vessel for storing fluids such as hydrogen using liners 100 and 110 are well known to those skilled in the art.

[0037] This specification includes the following components: [1] A method for manufacturing a liner for a pressure vessel, The liner comprises a main body having a central portion and a tapered portion, and a plurality of connecting portions that connect two adjacent main body portions in series via the tapered portion, and which have a smaller diameter than the central portion and are bent to fold the main body portion. A manufacturing method comprising the step of manufacturing a liner by extruding a cylindrical preform having a predetermined inner diameter, and placing a cylindrical molding auxiliary member having an outer diameter corresponding to the inner diameter of the connecting portion inside the portion of the preform that corresponds to the connecting portion, and hollow molding the liner while the auxiliary member is in contact with the inside of the connecting portion. [2] The manufacturing method according to [1], wherein the step includes using a mold set comprising a plurality of pairs of molds arranged on a predetermined track facing the pre-molded body. [3] The manufacturing method according to [1] or [2], wherein the step includes forming the connecting portion so as to provide a groove on the inner outer surface when the connecting portion is bent. [4] The manufacturing method according to any one of [1] to [3], further comprising the step of bending the connecting portion of the liner. [5] Liner of a pressure vessel, The liner comprises a main body having a central portion and a tapered portion, and a plurality of connecting portions that connect two adjacent main body portions in series via the tapered portion, having a smaller diameter than the central portion and being bent to fold the main body portion. Equipped with, The connecting portion is a liner having a thickened portion between it and at least one of the adjacent tapered portions.

[0038] The technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated herein or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself. [Explanation of Symbols]

[0039] 4 Main body, 6 Space, 10 Main body, 12 Central section, 14 Tapered section, 20 Connecting section, 22 Groove section, 24 Thick section, 30 Pre-molded body, 40 Molding die set, 42, 44, 46 Molding die, 48 Convex molding section, 50 Molding auxiliary member, 52 Ventilation hole, 100 Liner (before bending), 110 Liner after bending, 200 Molding device

Claims

1. A method for manufacturing a liner for a pressure vessel, The liner comprises a main body having a central portion and a tapered portion, and a plurality of connecting portions that connect two adjacent main body portions in series via the tapered portion, and which have a smaller diameter than the central portion and are bent to fold the main body portion. A manufacturing method comprising the step of manufacturing a liner by extruding a cylindrical preform having a predetermined inner diameter, and placing a cylindrical molding auxiliary member having an outer diameter corresponding to the inner diameter of the connecting portion inside the portion of the preform that corresponds to the connecting portion, and hollow molding the liner while the auxiliary member is in contact with the inside of the connecting portion.

2. The manufacturing method according to claim 1, wherein the step includes using a mold set comprising a plurality of pairs of molds arranged to face each other on a predetermined track.

3. The manufacturing method according to claim 1, wherein the step includes forming the connection portion so as to impart a groove shape to the inner outer surface when bent.

4. Furthermore, the manufacturing method according to any one of claims 1 to 3, further comprising the step of bending the connecting portion of the liner.

5. Liner of a pressure vessel, The liner comprises a main body having a central portion and a tapered portion, and a plurality of connecting portions that connect two adjacent main body portions in series via the tapered portion, having a smaller diameter than the central portion and being bent to fold the main body portion. Equipped with, The connecting portion is a liner having a thickened portion between it and at least one of the adjacent tapered portions.

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